No. 921

Title:

The genetic Cox processes quantified two functions of preserved mature trees after shelterwood harvesting: providing seed sources and safe sites

Author(s):

SHIMATANI, Kenichiro (The Institute of Statistical Mathematics); KITAMURA, Keiko (Hokkaido Research Center, Forestry and Forest Products Research Institute); KANAZASHI, Tatsuro (Tohoku Research Center, Forestry and Forest Products Research Institute); SUGITA, Hisashi (Tohoku Research Center, Forestry and Forest Products Research Institute)

Key words:

cluster; genetics; safe site; seed dispersal; Cox process; shelterwood; spatial pattern.

Abstract:

Clustering distribution of a plant population can be formed by limitedly dispersed seeds as well as patchily distributed safe sites, and an application of the Cox process to spatial individual distribution cannot distinguish the two ecological mechanisms. For example, when matured trees of shade-tolerant species are preserved in isolation such as under shelterwood management system, it is often seen that saplings are clustering around the preserved adults. However, saplings beneath a crown are not necessarily that adult’s daughters. In particular, by means of reducing competition with shade-intolerant fast-growing species, the crown might provide safe sites with shade-tolerant saplings, resulting in the clustering of that species. Genotypic data provide kinship information between adults and offspring and the Cox process can be improved to a marked point process incorporating genotypes. Combining the general and the genetic Cox process, this paper introduces spatial models that reflect the two roles of preserved adults; providing seed sources and forming safe sites. The former is expressed by the conditional probability that a sapling has a given genotype given that it appears there, and the maximum likelihood method can be separately conducted for the two components. The models were applied to two secondary beech (Fagus crenata) forests regenerated after shelterwood harvesting in Japan. The results quantitatively estimate fat-tailed seed dispersal after the harvesting as well as the effects of crowns on forming safe sites.